JP2002136835A - Two-chamber type wet flue gas desulfurization apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wet type flue gas desulfurization apparatus which is capable of steadily support a spray header while preventing the channeling of a gas in an ascending flow area and a descending flow area in a two-chamber type absorption tower and which exhibits a high desulfurization rate. SOLUTION: The spay header 18 is inserted into the absorption tower from the wall face of the tower, which wall face forms the descending flow area 13 partitioned by a partition plate 4 provided at the inside of the tower, and the tip end part of the spray header 18 perforated through the partition plate 4 is supported by the wall face of the tower, which wall face forms the ascending flow area 12. The spray header 18 having a form such that the rates of the space in the tower limited by the volume occupied by the spray header in each of the ascending flow area 12 and the descending flow area 13 become nearly same is used, and the diameter of the pipe of the spray header 18 and the number of spray nozzles 16 and 17 are controlled so that the amounts of an absorption liquid sprayed from the spray nozzles 16 and 17 per unit cross sectional area perpendicular to the gas flow direction in each of the ascending low area 12 and the descending flow area 13 become nearly same.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet flue gas desulfurization apparatus for removing sulfur oxides in exhaust gas discharged from a combustion apparatus such as a boiler, and more particularly, to a method for installing a partition plate inside an absorption tower. In a two-chamber desulfurization device divided into two gas-liquid contact parts, an upflow region where exhaust gas flows upward and a downward flow region where it flows downward, a function that can prevent gas drift in the upward flow region and the downward flow region The present invention relates to a two-chamber wet-type flue gas desulfurization apparatus provided.

[0002]

2. Description of the Related Art Sulfur oxides in flue gas generated by fossil fuel combustion in thermal power plants and the like, particularly sulfur oxides, are one of the main pollutants in environmental problems such as air pollution and acid rain. In recent years, the spread of flue gas desulfurization equipment on a global scale has been desired.

[0003] As a current desulfurization system, a wet method based on a limestone-gypsum method occupies the mainstream, and among them, a spray method, which is the most proven and highly reliable, is widely used worldwide. This spray type desulfurization device has high desulfurization performance, and the basic technology is almost established.

[0004] However, since the above-mentioned wet flue gas desulfurization apparatus is expensive, its penetration rate in developing countries is still low.
Therefore, to increase the penetration rate of desulfurization equipment worldwide,
It is necessary to significantly reduce equipment costs and operation costs of the desulfurization unit.

FIGS. 5 to 7 show a conventional two-chamber wet flue gas desulfurization apparatus which adopts a spray method and reduces cost.

This wet flue gas desulfurization apparatus mainly comprises an absorption tower main body 1, an inlet duct 2, an outlet duct 3, a partition plate 4, an absorption liquid circulation pump 5, a circulation tank 7, a stirrer 8, an air blowing pipe 9, a mist eliminator. 10. Absorbent extraction pipe 11,
It comprises an upflow area 12, a downflow area 13, a circulation pipe 14, spray nozzles 16 to 17, a spray header 18, and the like.

[0007] A plurality of spray nozzles 16 and 17 are provided in a cross section of the absorption tower orthogonal to the gas flow, and a plurality of spray nozzles are provided in the gas flow direction. Also,
The stirrer 8 and the air blowing pipe 9 are installed in the circulation tank 7 through which the absorbent flows, and the mist eliminator 10 is installed in the outlet duct 3.

Exhaust gas discharged from a boiler (not shown) is introduced into the absorption tower main body 1 from an inlet duct 2 in a substantially horizontal direction by a desulfurization fan (not shown), and is discharged from an outlet duct 3 after being desulfurized. .

Most of the absorption towers of the spray method discharge exhaust gas introduced from the lower part of the absorption tower from the tower top in order to bring the exhaust gas and the absorbing liquid into countercurrent contact, but the prior art shown in FIG. 1, the partition plate 4 is installed, and the outlet duct 3 is provided at substantially the same height as the inlet duct 2.
The exhaust gas introduced from the inlet duct 2 is blocked by the partition plate 4, rises in the upflow region 12, reverses at the top of the tower, and then descends in the downflow region 13. During this time, in the ascending flow region 12 and the descending flow region 13, the absorption liquid containing calcium carbonate sent from the absorption liquid circulation pump 5 is injected from the spray nozzles 16 and 17 provided in the respective regions, and the absorption liquid and the exhaust gas are discharged. Gas-liquid contact is made.

At this time, the absorbing liquid selectively absorbs sulfur oxides in the exhaust gas to generate calcium sulfite. The absorption liquid that has generated calcium sulfite temporarily accumulates in the circulation tank 7 and, while being stirred by the oxidizing stirrer 8, is oxidized by oxygen in the air supplied from the air blowing pipe 9 to generate calcium sulfate (gypsum). I do.

A part of the absorbent in the circulation tank 7 where calcium carbonate and gypsum coexist is sent again to the spray nozzles 16 and 17 by the absorbent circulation pump 5, and a part is not shown through the absorbent extraction pipe 11. Sent to waste liquid treatment and gypsum recovery system. Among the absorption liquids atomized by spraying from the spray nozzles 16 and 17, those having a small droplet diameter are accompanied by the exhaust gas, but are collected by the mist eliminator 10 provided in the outlet duct 3.

In order to make the amount of the absorbing liquid ejected from the spray nozzles 16 and 17 attached to the spray header 18 as uniform as possible in each of the nozzles 16 and 17, the spray header 18 has a thicker root near the circulation pipe 14 and has a larger diameter. Generally, the distal end far from the pipe 14 is thinned.

In the prior art, a spray header 18 to which spray nozzles 16 to 17 are attached is inserted into the absorption tower main body 1 from a direction parallel to the partition plate 4 as shown in FIG. For this reason, the space where the exhaust gas actually flows becomes narrower on the root side of the spray header 18 and conversely widens on the tip side of the spray header 18. As described above, when there is a difference in the porosity indicating the ratio of the cross section in which the exhaust gas actually flows in the cross section of the absorption tower, the exhaust gas drifts, and the desulfurization rate tends to decrease. This tendency is due to the absorption tower structure shown in FIG.
That is, when the width of the absorption tower becomes large, it appears remarkably,
The difference in porosity between the root portion side and the tip portion side of the spray header 18 is further increased.

The spray header 18 has a structure of both ends supported by the tower walls on both sides. When the width of the absorption tower is increased as shown in FIG. 7, a downward bending moment due to the weight of the spray header 18 itself is obtained. And spray nozzle 1
Since the bending moment due to the reaction force generated by the injection of the absorbing liquid from 6 to 17 increases, a strong supporting steel frame capable of absorbing the moment is required.

Further, a force acts on the partition plate 4 due to the wind pressure of the exhaust gas blown from the inlet duct 2, the pressure difference between the upflow region 12 and the downflow region 13, the collision of spray droplets, and the like. A tough supporting steel frame that can prevent the vibration of the partition plate 4 is required, which increases the equipment cost.

Further, in the downflow region 13, the absorbing liquid and the exhaust gas are in co-current contact, and the relative speed between the two cannot be sufficiently obtained, so that the absorbing speed of the sulfur oxide tends to decrease. Therefore, in order to ensure high desulfurization performance even in the downflow region 13, it is necessary to increase the exhaust gas flow rate in the downflow region 13. However, the outlet duct 3 in which the mist eliminator 10 is installed is connected to the downstream of the descending flow region 13.
/ S, it is necessary to decelerate to about
If the flow rate of the exhaust gas in Step 3 is too high, the gas will drift greatly at the inlet of the mist eliminator 10 and the mist collection performance of the mist eliminator 10 will be reduced.

[0017]

In the above prior art, the gas drift in the upflow region and the downflow region in the two-chamber absorption tower, the method of supporting the spray header and the partition plate, the gas drift at the inlet of the mist eliminator, etc. However, there has been a problem that the desulfurization rate, the mist collection performance deteriorates, and the equipment cost increases.

An object of the present invention is to provide a wet flue gas desulfurization system which strongly supports a spray header while preventing gas drift in an upflow region and a downflow region in a two-chamber absorption tower, and has a high desulfurization rate and high mist collection performance. It is to provide a device.

[0019]

The object of the present invention is to provide a spray nozzle which sprays an absorbing liquid, and a spray header penetrates a partition plate which partitions an upflow area and a downflow area of a two-chamber absorption tower, and This is achieved by temporarily increasing the diameter of the spray header from the gas inlet side to the gas outlet side.

That is, the present invention provides a circulation tank for storing an absorbent slurry, an inlet duct for introducing exhaust gas discharged from a combustion device such as a boiler in a substantially horizontal direction above the circulation tank, and a purified exhaust gas. An outlet dust that is discharged in a substantially horizontal direction, an exhaust gas channel is provided between the inlet duct and the outlet duct, and a ceiling portion for dividing the exhaust gas channel into two chambers on the inlet duct side and the outlet duct side. There is an opening in the upper part of the ascending flow area where the exhaust gas introduced from the inlet duct flows upward by providing a vertical partition plate with the lower end part immersed in the absorbent in the circulation tank. A downflow region is formed in which exhaust gas flows downward toward the outlet duct after being reversed at the section, and a spray nozzle for ejecting the absorbing liquid supplied from the circulation tank is installed in each region, and the spray nozzle is provided. A two-chamber wet exhaust system equipped with an absorption tower for treating sulfur oxides in exhaust gas, which is arranged so that the absorbing slurry and the exhaust gas ejected from the nozzle are brought into countercurrent contact in the upflow region and cocurrent in the downflow region. In the desulfurization device, a two-chamber wet discharge system in which a spray header having a spray nozzle for ejecting an absorbing liquid penetrates a partition plate, and the pipe diameter of the spray header is temporarily increased from an exhaust gas inlet side to an exhaust gas outlet side. It is a smoke desulfurization unit.

The object of the present invention is to provide a spray header having a diameter from the gas inlet side to the gas outlet side of the absorption tower.
It is also achieved by increasing the size in at least two stages.

Furthermore, the above object of the present invention can also be achieved by increasing the diameter of the spray header in at least two stages in the upflow region in the absorption tower.

More specifically, the object of the present invention is to reduce the porosity in the column, which is limited by the volume occupied by the spray header in each space in the upflow region and the downflow region divided by the partition plate. Using spray headers of the same shape, or absorbing liquid ejected from the spray header per unit cross-sectional area perpendicular to the gas flow direction in each space of the upflow area and the downflow area divided by the partition plate The problem can be solved by setting the diameter of the spray header and the number of spray nozzles so that the amounts are almost the same.

More specifically, the object of the present invention is to insert a spray header into a tower from a wall of a tower which forms a downward flow region facing a partition plate in an absorption tower, and penetrate the partition plate. This problem is solved by supporting the tip of the spray header on the tower wall surface in the upflow area facing the partition plate.

[0025]

In the case of a two-chamber wet desulfurization device, the inside of the absorption tower is divided into an upflow region and a downflow region by a partition plate. Each horizontal cross-sectional shape is usually rectangular, and when viewed from the inlet duct side to the outlet duct side, the distance between the tower wall and the partition plate in the direction perpendicular to the partition plate is smaller than the distance between the left and right tower walls. Is shorter.

In the present invention, since the spray header is installed so as to penetrate the partition plate from a direction perpendicular to the partition plate, the amount of the ejected absorbent from the spray nozzle can be reduced in any of the upward flow region and the downward flow region. In order to make the unit cross-sectional area in the exhaust gas flow direction substantially uniform, the number of tapered steps of the spray header is small, and the change in the porosity in the column in the direction perpendicular to the partition plate is small. Therefore, the drift of the exhaust gas due to the difference in the porosity in the tower which is limited by the volume occupied by the spray header in the upflow region and the downflow region is reduced.

The spray header has a beam structure supported at both ends supported by the tower wall and the partition plate. However, since the distance between the tower wall and the partition plate in the direction perpendicular to the partition plate is short as described above, The downward bending moment due to the weight of the spray header itself filled with the absorbing liquid and the bending moment due to the reaction force generated by the ejection of the absorbing liquid from the spray nozzle are also reduced. Therefore, depending on conditions, a supporting steel frame for absorbing the moment can be omitted, and even if a supporting steel frame is installed, a simple supporting steel frame is sufficient.

Further, a force due to the wind pressure of the exhaust gas blown from the inlet duct, the pressure difference between the upflow region and the downflow region, the collision of spray droplets, etc. acts on the partition plate. Is the collision of the spray droplets, and the portion where the droplets directly collide with the partition plate is particularly likely to generate vibration.

However, in the present invention, since the spray header supports the partition plate, it is possible to prevent the occurrence of vibration and to omit or simplify the supporting steel frame.

Further, since the spray header is inserted into the tower from the tower wall on the exit duct side, the spray header in the descending flow area becomes thick and occupies a large amount of the descending flow area. Even if the cross-sectional area of is larger than the cross-sectional area of the upflow area and the gas flow rate in the downflow area is set lower than that of the upflow area, only the gas flow rate near the spray nozzle can be increased. Therefore, the relative speed between the droplet ejected from the spray nozzle and the exhaust gas is increased, and high desulfurization performance can be obtained.

If the superficial gas flow velocity in the downflow region in the tower can be set slower than that in the ascending flow region, the gas drift at the mist eliminator entrance in the outlet duct will also be small, so that the mist collection performance is prevented from deteriorating. It is also possible.

[0032]

Embodiments of the present invention will be described below with reference to the drawings. The embodiment of the present invention shown in FIG. 1 is a side view of an absorption tower, which is mainly composed of an absorption tower main body 1 and an inlet duct 2 like the conventional wet flue gas desulfurization apparatus shown in FIGS. Outlet duct 3, partition plate 4, absorption liquid circulation pump 5, circulation tank 7, stirrer 8, air blowing pipe 9, mist eliminator 10, absorption liquid extraction pipe 11,
It comprises an upflow area 12, a downflow area 13, a circulation pipe 14, spray nozzles 16 to 17, a spray header 18, and the like. A plurality of spray nozzles 16 and 17 are provided in a cross section orthogonal to the gas flow, and a plurality of spray nozzles are provided in the gas flow direction. Further, the stirrer 8 and the air blowing pipe 9 are installed in the circulation tank 7 through which the absorbing liquid flows, and the mist eliminator 10 is installed in the outlet duct 3.

The feature of the embodiment of the absorption tower shown in FIG. 1 is that the partition plate 4 is penetrated by the spray header 18 inserted from the tower wall surface of the exhaust gas descending flow area 13 in the absorption tower main body 1, and the tip of the spray header 18 is It is configured to be fixed to the inner wall of the tower in the upflow region 12. FIG. 2 is a view taken along line AA of FIG. FIG. 3 shows a case where the width of the absorption tower in the embodiment of FIG. 2 is further increased. FIG. 4 shows an embodiment in which the number of stages in which the thickness of the spray header 18 changes in the embodiment of FIG. 3 is two in the downward flow region 13 and three in the upward flow region 12.

In the embodiment shown in FIGS. 1 and 2, the spray header 18 is inserted into the tower from a direction perpendicular to the partition plate 4, and the spray header 18 is inserted from the downflow region 13 side.
Is different from the prior art in that

In order to make the amount of the absorbing liquid jetted from the spray nozzles 16 and 17 per unit cross-sectional area of the gas passage in the cross section inside the absorption tower perpendicular to the gas flow uniform, the spray header 1
8 is to thicken the base near the circulation pipe 14 and
It is necessary to make the tip far from the head thinner.

On the other hand, in the case of a rectangular two-chamber absorption tower, the horizontal cross-sectional shape of each of the ascending flow region 12 and the descending flow region 13 is rectangular. The distance between the tower wall and the partition plate 4 in the direction orthogonal to the partition plate 4 is shorter than the width between the tower walls.

In this embodiment, since the spray header 18 is inserted from a direction perpendicular to the partition plate 4, the number of tapered steps of the spray header 18 can be reduced, and the inside of the tower in the direction perpendicular to the partition plate 4 can be reduced. Small change in porosity. Therefore, the gas drift due to the difference in porosity is reduced, and a decrease in desulfurization performance can be prevented.

The spray header 18 has a support beam structure supported at both ends by the tower wall and the partition plate 4. As described above, the distance between the tower wall and the partition plate 4 in the direction perpendicular to the partition plate 4 is as described above. Is shorter, the downward bending moment due to the weight of the spray header 18 itself filled with the absorbing liquid and the bending moment due to the reaction force generated by the ejection of the absorbing liquid from the spray nozzles 16 and 17 are also reduced. A supporting steel frame for absorption can be omitted, and even if a supporting steel frame is installed, a simple one is sufficient.

Further, the entrance duct 2 is connected to the partition plate 4.
The force due to the wind pressure of the exhaust gas blown from the air, the pressure difference between the upflow region 12 and the downflow region 13, and the collision of the spray droplets acts, the largest of which is the collision of the spray droplets. Vibration is particularly likely to occur in a portion that directly collides with the partition plate 4. However, in the configuration of the present embodiment, since the spray header 18 supports the partition plate 4, it is possible to prevent the occurrence of vibration and to omit or simplify the supporting steel frame.

Further, the spray header 18 is moved down the downflow region 1.
Since it is inserted from the third side, the pipe diameter of the spray header 18 in the downflow region 13 becomes larger than that in the upflow region 12, and occupies a larger portion of the empty tower section in the downflow region 13.

Therefore, the cross-sectional area in the direction perpendicular to the gas flow in the downflow region 13 is increased in advance, and the gas flow velocity is set to be low. However, since the gas flow path is narrowed by the spray header 18 near the spray nozzle 17, only the gas flow velocity near the spray nozzle can be increased, and the spray nozzle 1
7, the relative speed between the droplets ejected from 7 and the exhaust gas increases, and high desulfurization performance can be obtained.

Also, if the superficial gas flow velocity in the downflow region 13 can be set low, the gas drift at the entrance of the mist eliminator 10 in the outlet duct 3 will also be small, so that it is possible to prevent the mist trapping performance from lowering. .

The embodiment shown in FIG. 3 differs from the embodiment shown in FIG. 2 in that the width of the absorption tower in the embodiment shown in FIG. 2 is increased. In the example shown in FIG. 3, the width between the tower walls on both sides when the outlet duct 3 is viewed from the inlet duct 2 side is larger than that in the example shown in FIG.
Since the length of 8 and the number of tapering steps do not change, the change in the porosity is small as in the embodiment shown in FIG. 2, and the gas drift is not promoted.

The embodiment shown in FIG. 4 differs from the embodiment shown in FIG. 3 in that the number of tapering steps of the spray header 18 in the embodiment shown in FIG. 3 is increased. Even if the number of tapered steps of the spray header 18 itself increases, the middle thereof is partitioned by the partition plate 4, so that the number of tapered steps in each space of the ascending flow area 12 and the descending flow area 13 may be about 2 to 3 steps, There is little change in the space through which the gas flows. Therefore, the gas drift in the spray portion is smaller than in the prior art.

[0045]

According to the present invention, since the change in porosity near the spray header can be minimized, the upflow region, the downflow region, and the mist eliminator inlet of the exhaust gas partitioned by the partition plate in the absorption tower are reduced. , Gas drift is reduced, and a decrease in desulfurization performance and mist collection performance can be prevented.
Further, the supporting steel frame of the spray header and the partition plate can be omitted or simplified, and the equipment cost can be reduced.

[Brief description of the drawings]

FIG. 1 shows a side view of an absorption tower according to an embodiment of the present invention, in which a spray header inserted from a tower wall surface in a descending flow region penetrates a partition plate and a tip of the spray header is fixed to a tower inner wall in an upward flow region. It is a thing.

FIG. 2 is a view taken along the line AA of FIG. 1;

FIG. 3 is a plan view of the embodiment when the width of the absorption tower in FIG. 2 is increased.

4 is a plan view of an embodiment in which the number of stages in which the thickness of the spray header of the absorption tower in FIG. 3 changes is increased to two stages in the downflow region and three stages in the upflow region.

FIG. 5 is a side view of an absorption tower in a conventional two-chamber wet flue gas desulfurization apparatus.

FIG. 6 is a view taken along the line AA of FIG. 5;

FIG. 7 is a plan view when the width of the absorption tower in FIG. 6 is increased.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Absorber tower main body 2 Inlet duct 3 Outlet duct 4 Partition plate 5 Absorbent liquid circulation pump 7 Circulation tank 8 Stirrer 9 Air blowing pipe 10 Mist eliminator 11 Absorbent liquid extraction pipe 12 Upflow area 13 Downflow area 14 Circulation pipe 16 Spray nozzle 17 Spray nozzle 18 spray header

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Hirofumi Yoshikawa 3-36 Takara-cho, Kure-shi, Hiroshima Babcock-Hitachi Inside Kure Research Laboratories (72) Naoki Oda 6-9 Takara-cho Kure-shi, Hiroshima Babcock-Hitachi, Ltd. F-term in Kure Plant (reference) 3K070 DA03 DA16 DA23 DA28 DA38 DA73 4D002 AA02 AB01 AC01 BA02 CA01 DA05 DA16 EA03 EA12 EA20 FA03

Claims (6)

[Claims] 1. A circulation tank for storing an absorbent slurry, an inlet duct for introducing exhaust gas discharged from a combustion device such as a boiler in a substantially horizontal direction above the circulation tank, and a purified exhaust gas in a substantially horizontal direction. An outlet dust to be discharged is provided, an exhaust gas flow path is provided between the inlet duct and the outlet duct, and an opening is formed on a ceiling side for dividing the exhaust gas flow path into two chambers on the inlet duct side and the outlet duct side. By having a vertical partition plate in which the lower end is immersed in the absorption liquid in the circulation tank, the exhaust gas introduced from the inlet duct is inverted at the upward flow area where the upward flows and the opening on the ceiling side Later, a downward flow area in which exhaust gas flows downward toward the outlet duct is formed, and spray nozzles for ejecting the absorbing liquid supplied from the circulation tank are installed in the respective areas, and the spray nozzles eject from the spray nozzles. -Chamber wet exhaust desulfurization unit equipped with an absorption tower for treating sulfur oxides in exhaust gas, arranged so that the absorbent slurry and exhaust gas come into countercurrent contact in the upflow region and cocurrent contact in the downflow region In the two chambers, a partition plate is penetrated by a spray header to which a spray nozzle for ejecting an absorbing liquid is attached, and the pipe diameter of the spray header is temporarily increased from an exhaust gas inlet side to an exhaust gas outlet side. Type wet flue gas desulfurization equipment. 2. The two-chamber wet-type flue gas desulfurization apparatus according to claim 1, wherein the diameter of the spray header is increased in at least two stages from the gas inlet side to the gas outlet side. 3. The two-chamber wet flue gas desulfurization apparatus according to claim 1, wherein the diameter of the spray header is increased in at least two stages in an upflow region. 4. A spray header whose shape is such that the porosity in the tower, which is limited by the volume occupied by the spray header in each space in the upflow region and the downflow region separated by the partition plate, is substantially the same. The two-chamber wet-type flue gas desulfurization apparatus according to any one of claims 1 to 3, characterized in that: 5. An absorption liquid ejected from a spray header per unit cross-sectional area orthogonal to a gas flow direction in each space of an upflow region and a downflow region partitioned by a partition plate, so as to have substantially the same amount. 5. The two-chamber wet flue gas desulfurization apparatus according to claim 1, wherein the diameter of the spray header and the number of spray nozzles in each area are selected and provided. 6. A spray header is inserted into a tower from a wall of a tower forming a downward flow region facing a partition plate in an absorption tower,
The two-chamber wet smoke exhaust system according to any one of claims 1 to 5, wherein a tip portion of the spray header is supported by a tower wall surface in an upflow area that penetrates through the partition plate and faces the partition plate. Desulfurization equipment.